X = int(input())

A = 2
B = -1

move = [2, 2, -1, -1, 2, -1, -1]
now_point = 0
move_total = 0

for i in range(100):
    for j in move:
        now_point += j
        move_total += abs(j)
        if now_point == X:
            print(move_total)
            break